This disclosure relates to articles having a layer, such as an abradable layer, that includes a metal phase and ceramic phases.
Components that are exposed to high temperatures, such as gas turbine engine components, typically include a protective coating system having one or more coating layers. For example, air seals located radially outwards of rotating engine blades in the turbine section typically include the coating system to protect from erosion, oxidation, corrosion or the like and also to facilitate efficient operation of the engine. In the compressor and fan sections where temperatures are within the temperature capability of metal alloys, the coating layer(s) are designed primarily to minimize blade tip clearance to the outward air seals. However, some air seals are radially inward when vanes are supported at the outer diameter and seal against the rotating shaft.
Some conventional air seals include an abradable layer that contacts tips of the blades during engine operation such that the blades abrade the layer upon operation of the engine. The abrasion between the layer and blade tips provides a minimum clearance between these components to reduce gas flow around the tips of the blades and thereby facilitate efficient interaction between the gas flow and the blades.
Although effective, existing abradable layers can be expensive to manufacture. For example, a plasma spray process may be used to deposit a powder onto an air seal as the abradable layer. However, the powder does not strongly adhere to the air seal during the spray process. Therefore, a significant amount of powder may be consumed in the spray process without being deposited onto the air seal, which contributes to the expense of manufacturing.